[TIMOB-16533] Android: Button does not resize image to fit within boundaries

If you create a button view with an image:

var button = Ti.UI.createButton({
  image : "/images/my-icon.png"
  width : Ti.UI.SIZE,
  height : 40
  title : "My Button"
});

if the image is taller than 40, it will be cropped, rather than scale to fit in the available space. This isn't really an issue on iOS, as there are only two image size choices, but on Android, a 2x (XHDPI) image may be chosen, even if the interface is scaled by some other method. Thus the image may be cropped.